yao2030

(define (union-set set1 set2)
  (cond ((null? set1) set2)
  ((null? set2) set1)
	((element-of-set? (car set1) set2)
	 (union-set (cdr set1) set2))
	(else 
	 (cons (car set1) (union-set (cdr set1) set2)))))

yao2030

;;sets as order lists

(define (element-of-set? x set)
  (cond ((null? set) false)
	((= x (car set)) true)
	((< x (car set)) false)
	(else (element-of-set? x (cdr set)))))
(define (intersection-set set1 set2)
  (if (or (null? set1) (null? set2))
      '()

yao2030

;; capitalize 
M-c
M-- M-c
;; Upper case
M-u
M-- M-u
;; lower case
M-l
M-- M-l

yao2030

;; quit message
(fset 'yes-or-no-p 'y-or-n-p)
;;把缺省的 major mode 设置为 text-mode, 而不是几乎什么功能也
;;没有的 fundamental-mode.
(setq default-major-mode 'text-mode)
(setq initial-major-mode 'text-mode)
;;光标靠近鼠标指针时，让鼠标指针自动让开，别挡住视线。
(mouse-avoidance-mode 'animate)
;;显示列号
(setq column-number-mode t) 

yao2030

(define (memq item x)
  (cond ((null? x) false)
	((eq? item (car x)) x)
	(else (memq item (cdr x)))))
;; huffman coding (information theory)
(define (make-leaf symbol weight)
  (list 'leaf symbol weight))
(define (leaf? object)
  (eq? (car object) 'leaf))
(define (symbol-leaf x) (cadr x))

yao2030

;; 3.1
(define (make-accumulator init)
  (lambda (x)
    (set! init (+ init x))
    init))
;; 3.2
(define (make-monitored f)
  (let ((count 0))
    (lambda (m)
      (cond ((eq? m 'how-many-calls) count)

yao2030

(define (random-in-range low high)
  (let ((range (- high low)))
    (+ low (random range))))
(define (experiment x1 x2 y1 y2)
  (let ((a (random-in-range x1 x2))
	(b (random-in-range y1 y2))
	(c (/  (+ x1 x2) 2.0))
	(d (/  (+ y1 y2) 2.0))
	(r (/ (- x1 x2) 2.0)))
    (<= (+ (square (- a c))

yao2030

;; selectors
(define (front-ptr queue) (car queue))
(define (rear-ptr queue) (cdr queue))
(define (set-front-ptr! queue item) (set-car! queue item))
(define (set-rear-ptr! queue item) (set-cdr! queue item))
(define (empty-queue? queue) (null? (front-ptr queue)))
;; constructors
(define (make-queue) (cons '() '()))
;; selectors
(define (front-queue queue)

yao2030

(define (make-queue)
  (let ((front-ptr '())
	(rear-ptr '()))
    (define (set-front-ptr! item)
      (set! front-ptr item))
    (define (set-rear-ptr! item)
      (set! rear-ptr item))
    (define (empty-queue?)
      (null? front-ptr))
    ;; (define (print-queue)

yao2030

(load "stream-map.ss")
(load "ex59")

(define (scale-stream s f)
  (stream-map (lambda (x) (* x f)) s))
(define (mul-series s1 s2)
  (cons-stream (* (stream-car s1)
		  (stream-car s2))
	       (add-streams
		(scale-stream (stream-cdr s2) (stream-car  s1))